Another story out of Italy this week is very similar, except that it takes place in the 5th-6th centuries. Archaeologists found a pair of skeletons outside ancient Mutina (modern Modena) that appear to have been looking at one another and holding hands. The skeletons are not in particularly good shape, but they do appear to be those of a man (on the left) and a woman (on the right). Donato Labate, the director of the archaeological excavation, suggests that the two had been looking at one another but that the man's head moved postmortem - which seems plausible considering the twisted neck vertebrae in the photograph.

Also found was a bronze ring - hard to tell exactly in the jumble of poorly preserved bones, but it seems to be on the woman's right hand. Wedding rings have a long history in the Old World (well, for women - men don't need rings since they weren't property), so it's entirely possible that this was a married couple. With the number of plagues that ravaged Europe, it's also entirely possible the couple died close to the same time. Then again, multiple burials are not unheard of in ancient Italy, so there could be another explanation.

The most interesting thing about the Lovers of Modena (5th-6th centuries AD) and the Lovers of Mantua (the so-called Romeo and Juliet, dating to 5,000-6,000 BC) is that whoever buried them felt the need to communicate their relationship in death. We don't bury ourselves, of course, but we can only speculate as to who buried these couples (their kids? their parents? the community?) and why they buried them in a rather anomalous way.

October 19, 2011

I fear I will be accused of padding out this edition of the Roman bioarchaeology carnival with my own posts, but some weeks I feel the need to devote more in-depth coverage (i.e., a stand-alone post) to a new find than to others.

Excavations and Finds

Was it murrrrrder?

October 5. The skeletons of three men dating to the 1st c BC to 1st c AD were found outside of Modena, Italy, and archaeologists think they were murdered because of the burial style and the presence of sharp trauma (cut marks) on the bones. Only the Italian media has covered the find so far (with the best coverage at La Repubblica and best pictures at Gazzetta di Modena), so I summarized the find in my post "Mutiny in Mutina? Decapitated Slaves in Roman Modena." [Photo from Gazzetto di Modena.]

Oldest Sardinian found

October 8. The oldest skeleton on the island of Sardinia has been found at the site of Marina di Arbus. Archaeologists have named the skeleton Amiscora, and the remains appear to have been that of a male. Amiscora joins a an adult male skeleton, "Beniamino," discovered in 1985 in the same region and covered in red ochre, as Neolithic-Mesolithic in date (roughly 8,500 years ago). So, not exactly Roman, but still quite interesting since the skeletons will help archaeologists understand when and how Sardinia was originally settled. [Photo from Adnkronos.com.]

October 12. Excavations have concluded on a Lombard cemetery at the fortress of Albornoz in Spoleto (central Italy). There aren't any further clues on the date (6th to 11th centuries AD?) and no information on whether there were skeletal remains. But the results of this year's excavation season will be presented in a public lecture next year.

October 17. Turkish archaeologists have discovered a Lycian tomb complex near the site of Rhodiapolis, dating to roughly 300 BC. It sounds like the tombs have been looted, so there may be no skeletal remains left, but the architecture of the tombs will prove key to understanding the burial program of Lycian Anatolia.

October 19. A dig at Poggio Colla, an Etruscan site in the Mugello Valley dating to about 600 BC, turned up not one but two incised fragments of bucchero, a glossy black pottery characteristic of pre-Roman times, that appear to depict a woman giving birth. Phil Perkins, an expert on bucchero, made the identification. Greg Warden, the director of the project, suggests that this find is extraordinary for its subject matter and its discovery at an elite sanctuary. This fragment appears to be the earliest depiction of childbirth in ancient Italy, with other representations not appearing until Republican Rome 500 years later. A paper about the find will be presented at the upcoming AIA meetings in Philly by Ann Steiner. An interesting blog post on the find and others like it comes from archaeologist Rosemary Joyce on her blog, Ancient Bodies, Ancient Lives. [Photo from ArtDaily.org.]

Data Analysis

Correlating geography and disease

October 11. Inspired by a lecture by bioarchaeologist Bethany Turner, who works at Machu Picchu, I correlated carbon and oxygen isotope results of my Roman skeletons with presence/absence of porotic hyperostosis (a condition that indicates the presence of anemia) in "Mapping Parasites in Ancient Italy". I found that the Romans were mostly not eating C4 foods (like millet) that could lead to dietary anemia, and that there was a significant difference in oxygen isotopes between the people with and without anemia. This suggests that people with high oxygen isotope values may have been from areas of Italy with endemic malaria or other parasites that caused anemia. More analyses are needed, of course, but this blog post represents the results of my playing around with my dissertation data to see what else I can learn about the Romans. [Graph by me.]

Publications

Tibia affected with treponemal
disease from Roman Spain

October 17. In an early-view article in the International Journal of Osteoarchaeology, Rissech and colleagues present evidence for treponemal disease from Roman Spain. The 25- to 30-year-old male's tibia (right) presented all the characteristics of syphilis, but without a complete cranium, the authors did not feel comfortable definitively stating this as a diagnosis. They are fairly confident that it is a treponemal infection, though, lending more weight to the pre-Columbian hypothesis for the origin of syphilis. I summarize the article in my post, "Morbus gallicus in the Roman Empire." [Photo from Rissech et al. 2011.]

October 18, 2011

In a story that has gotten surprisingly little international press, on October 5th researchers at the archaeological superintendency of Emilia-Romagna announced the discovery of a necropolis dating to the 1st century BC to 1st century AD along the ancient Roman via Emilia outside Modena (ancient Mutina). Discovered during excavations for a car park, the necropolis held mostly cremation burials. Three young males who weren't cremated, however, are the real news.

One man was about 18-25 years at death. His younger compatriot was a teenager, around 16-20 years at death, and was discovered with his skull between his legs. The oldest of the men, 24-30 years of age at death, was found with his arms crossed behind his back. As evidenced, the tableau of skeletons suggests quick, haphazard burial at the same time. Further, the archaeologists suggest that the bricks seen in the photograph were thrown in at the same time as the bodies.

The bioarchaeologist on the case is Vania Milani, whose previous work in the region includes the lovers of Modena and the mummies of Roccapelago. Milani found cutmarks on the bodies, although the news reports I read did not note precisely where they were located. Because of an absence of healing and periosteal reaction, Milani suggests that the cutmarks were made at or just after death. These men were buried in a cemetery that held only cremations, they were haphazardly buried together, and there is evidence of cutmarks, which leads Milani to conclude that, rather than postmortem burial ritual, these men were victims of homicide.

Under the dictatorship of Sulla, decapitation was a popular form of proscribed death. But Sulla generally wanted the heads as trophies. Since the heads of the murdered men from Mutina were present in the graves, the archaeologists suggest this was not a government-sanctioned killing. Rather, the director of the excavation, Donato Labate, told La Repubblica that they may have been slaves killed by their master, possibly as a lesson to other slaves (and the inclusion of bricks may have been to prevent them from re-emerging, he suggests, trying to jump on the recent witches/prostitutes/zombies bandwagon).

October 17, 2011

Italians called it the "French disease," the Dutch called it the "Spanish disease," the Russians called it the "Polish disease," and the Tahitians called it the "British disease." In the late 15th century, people around the world were blaming a particularly virulent, suddenly endemic disease on their improperly hygienic neighbors. The disease started off with a single chancre sore, then became a whole-body rash, and eventually caused people to go insane. In an era before antibiotics easily cured contagion, whole cultural groups needed someone to blame for mal de Naples, Arboyne pimple, Scottish sibbens, and Swedish saltfluss.

I'm talking, of course, about syphilis. In 1530, the Italian physician Girolamo Fracastoro created the neologism in an epic poem he wrote about a man who was cursed with disease by Apollo. Syphilus may have been named after the son of the nymph Niobe, mentioned as Sipylus in Ovid's Metamorphoses and himself named after a mountain in Turkey that Niobe fled back to when Artemis killed her daughters and Apollo killed her sons. Fracastoro both named the disease and got in a dig at his cultural neighbors with his book, Syphilis sive morbus gallicus ("Syphilis, or, The French Disease").

Between about 1495 and 1550, there is quite impressive historical evidence on epidemics of syphilis in Europe, but records before 1493 are less clear, which leads us to one of the most important discussions in palaeopathology: Did syphilis originate in the Old World or the New World? We don't yet have an answer to this question in part because we don't really know whether the treponemal diseases - venereal syphilis, endemic syphilis (bejel), yaws, and pinta - are all caused by one species of bacteria in the Treponema genus or by different species. And we don't have an answer yet because of the palaeopathological record itself: it's not a normal population, since it only has dead people; those skeletons that seem most healthy may be from people who died before a disease could progress to bony changes; not everyone is dug up from the ground, etc.

Since the first well-documented outbreak of syphilis happed in Naples, Italy, in 1494, the Columbian Exchange theory suggests that syphilis was a New World disease brought back by Columbus and his crew to Europe. Both skeletal evidence and recent genetic studies in the Americas seem to support the antiquity of a disease that was, if not modern syphilis, quite similar to the modern understanding of syphilis. On the other hand, the Pre-Columbian theory suggests that syphilis was present in Europe prior to Columbus' contact with the New World. Skeletal evidence of lesions that appear syphilitic in nature have been found in Europe dating to centuries before Columbus, and some palaeopathologists have concluded from rereading historical accounts that many descriptions of leprosy better fit the signs and symptoms of syphilis. Yet a third theory suggests that treponemal diseases were found all over the globe for tens of thousands of years but that contact between the previously isolated populations and/or other social and environmental conditions in the late 15th century caused the pathogen to mutate into a new disease that rapidly spread: venereal syphilis.

The authors' examination of the skeleton revealed that the left tibia was saber-shaped and that the upper half of its shaft was thickened. Further, the tibia had pitted areas and vascular grooves. A x-ray showed that the entire marrow cavity of the upper half of the tibia was completely closed up by new bone, and there was plenty of new bone formation on the outer surface of the tibia. These observations suggest a diagnosis of infectious disease that caused long-term inflammation. But was the infectious disease syphilis?

Bone changes occur in syphilis between 2-10 years after the onset of the infection (Ortner 2003). Most often, a person suffers changes in the tibia and cranium, particularly in venereal syphilis. The tibia often has expansion of the shaft of the bone and an excess of new bone (periostitis), resulting in the characteristic saber shape. Sometimes, the tibia also has osteomyeitis - an infection of the bone marrow that results in openings in the bone to allow for pus drainage. However, diagnosis of venereal syphilis specifically has generally rested on finding cranial lesions - the "worm-eaten" appearance known as caries sicca. While the cranial lesions characteristic of the treponematoses are quite unique to the disease, they are also quite rare, occurring in 14% of cases of venereal syphilis and in only 4% of cases of endemic syphilis, whereas lesions to the tibia are observed in 36% and 61% of cases of venereal and endemic syphilis, respectively. The skeletal remains of the man from Roman Spain do not include a cranial vault, meaning diagnosis of his condition can only be based on the tibia. The authors argue, however, that:

Fig. 9. Cross-sections of tibiae.
(Rissech et al. 2011)

the observed lesions of the tibia in the skeleton from Gava, characterized by encroachment into the medullary cavity of coarse cancellous bone, cancellization of the cortex, thickening of the diaphysis, the presence of small raised plaques of new bone bridging over minor blood vessels, a sabre-shaped morphology and a predominance of bone remodeling rather than periosteal reaction, are the typical characteristics of tibiae affected by treponematosis (Rissech et al. 2011, p. 10).

It's not news that Romans had venereal diseases (as the very word comes from the name of the Roman goddess of love) like gonorrhea, but the evidence for venereal syphilis prior to the Medieval period in Europe is sparse at the moment. Still, with perhaps 10,000 skeletons from Imperial Rome having been excavated in recent years and only cursorily studied, it is highly likely that palaeopathologists will soon begin to uncover more skeletal lesions and diagnose more diseases. And although the Romans didn't understand germ theory, the medical treatises of Galen, for example, are of immense help in our understanding of the epidemiology and presentation of a variety of diseases that afflicted the Romans.

So did the Romans have syphilis? The jury's still out, but I'm guessing there will be enough evidence soon for someone to add "insanity resulting from neurosyphilis" to the list of crazy theories for why the Roman Empire fell.

October 11, 2011

When I was an undergraduate at the University of Virginia, the fake major that everyone joked about was underwater basketweaving. I suspect there is a similar joke on every college campus, but I was surprised when Rick Scott, the governor of Florida, suggested that anthropology is a woo-woo field.

There's been a quick and passionate response from anthropologists and journalists around the web, including from the American Anthropological Association, Mother Jones, and the University of South Florida's anthropology department. A great smattering of links can be found on Daniel Lende's blog Neuroanthropology - Dr. Lende is an anthropology professor at USF.

What's coming out of this uproar - other than the realization that Rick Scott continues to show how smarmy and undereducated he is every time he opens his mouth - is that anthropologists are being given another wake-up call to make our field relevant. Some of us are trying to address the problem of lack of understanding of anthropology as a field by being public anthropologists: active on Twitter, blogging, sharing information on Facebook groups like BioAnthropology News. But as John Hawks points out in his excellent Anthropologies Project essay "What's wrong with anthropology?" we can do a whole lot more to fix the state of our discipline.

In my introductory anthropology courses, I address the importance of anthropology to today's college students at the beginning and the end of the semester. First and foremost, the focus of anthropology is on understanding yourself in relation to others. This may sound pretty simple, but it involves critically thinking about why you do what you do, why others do what they do, and what factors affect these actions: e.g., religion, economy, biology, politics, family structure, gender, ethnicity, etc. While we tend to deal with individuals in our line of work, we're also interested in the community - the commonalities in experience at various scales.

That's all well and good, you might say, but what skills do students learn in an anthropology course? Don't they just learn how to throw around adjectivized names like Foucauldian and Marxist? I tell my students - and then demonstrate as best as possible throughout the semester - that anthropologists do learn several key skills:

We learn clear, precise record-keeping skills and have to be attentive to detail. You have to observe what people say (and what they don't say), what they do (and what they don't do), what their bones or bodies tell you.

Anthropologists also learn analytical reading and critical thinking skills: how to read between the lines of a text, to question an author's or speaker's biases and the cultural context in which their ideas were formed. Thinking critically means questioning one's own biases in addition to those of others.

We also learn how to deal with unfamiliar social situations - we learn new languages and new rules for communication with people from all over the world, and we do this through participation in addition to observation so that we can understand where someone else is coming from.

Through these approaches, anthropologists want to understand the amazing variation in humankind - past and present - as well as the social and cultural context in which that variation occurred or is occurring. I think this is a powerful way to approach the world, but students aren't always convinced. How can anthropology help in the job search?, they ask.

The majority of my undergraduate students, particularly in the large lecture courses, will go into one of three main occupational spheres after graduation: health and medicine (doctors, nurses, genetics research, allied health fields, etc.), business and economics, and teaching (from preschool to PhDs). Anthropology is useful to all of these fields:

Medicine - The health professions aren't just about biology or chemistry or pharmacology. For example, is your African-American patient more likely to suffer hypertension because of his genetics or because of his diet? Anthropologists have tackled questions like these, with our dual emphases on biology and culture.

Business - You can crunch numbers in econ classes, but it only helps you predict what will happen under certain economic conditions. It is equally important to understand how individuals and cultures deal with money, for example, or how they react to global developments that have lasting effects on the way they see the world and act within it. Future business people can learn about the global economy and people's place within it through anthropology.

Teaching - This field isn't just about imparting facts for students to learn. A good teacher is attuned to a classroom that has seen many changes over the last few decades. My parents' generation was in high school when integration happened - and teachers are even today dealing with a pedagogical legacy that excludes certain ethnic or racial groups or is prejudiced against them. Today's teachers think long and hard about how to convey information in the best possible way, how to use multimedia, how to engage students who take different approaches to learning, how to remedy old curricula that focus largely on DWMs - dead white males. Future teachers can also benefit from understanding the main tenets of anthropology in designing lessons, engaging in instruction, and communicating with students and their parents.

In short, anthropology is useful for anyone whose future job will require them to develop the interpersonal skills to work with the public. And that includes just about every college graduate today.

I'd also go one step beyond saying that anthropology is imperative for college grads to work in a globalized market: anthropology needs to be brought into high schools. Many high schools around the country teach courses in psychology and sociology. Both of these are excellent options, but why not anthropology as well? The analytical and critical thinking skills we teach our students are fundamental to future jobs in many different fields, but it's our bio-cultural focus, our understanding of how we as living beings interact with our natural and cultural world, that sets us apart from psych and soc. And I think that's well worth teaching our high schoolers.

Let me close with a quotation from one of my favorite authors (and one-time anthropology student), Kurt Vonnegut, whose words - from an interview in 1973 - still ring true in our poor education of youth in anthropology:

I didn't learn until I was in college about all the other cultures, and I should have learned that in the first grade. A first grader should understand that his or her culture isn't a rational invention; that there are thousands of other cultures and they all work pretty well; that all cultures function on faith rather than truth; that there are lots of alternatives to our own society. Cultural relativity is defensible and attractive. It's also a source of hope. It means we don't have to continue this way if we don't like it.

Anthropology is a science, and Rick Scott's insistence that it be set apart from STEM fields shows that he fundamentally misunderstands what we do. Part of that is our fault, though, and we need to figure out ways to make anthropology more relevant. We don't have to continue this way if we don't like it.

Last week, Dr. Bethany Turner of Georgia State University gave a talk at Vanderbilt called, “Diet versus locale: isotopic support for causal influences in pathological conditions at Machu Picchu, Peru.” Bethany’s work centers on analysis of skeletal remains for multiple isotopes – Sr, O, Pb, C, and N – to investigate the heterogeneity of the population, which was composed of slaves, short-term (non-local) laborers, and locals. I greatly enjoyed the talk because, even though Machu Picchu is far removed in time and place, Bethany and I are using similar methods to answer similar questions about physical mobility in the past. Imperial Rome also, of course, had millions of slaves, as well as free immigrants who came looking for work and locals who were born there.

One of Bethany’s research questions was whether the immigrants were less healthy than the locals. In my dissertation research (Killgrove 2010), I investigated the frequencies of common diseases – osteoarthritis, dental caries, abscesses, linear enamel hypoplasias, and porotic hyperostosis – and found that immigrants to Rome were not significantly less healthy than locals, although they did seem to die at an earlier age (possibly of new diseases they were not immune to, possibly because the immigrant population had a different demographic profile than the locals did). Bethany took a slightly different approach to this question: she looked at porotic hyperostosis, which is a bony reaction to anemia that develops in childhood, and found that it was significantly correlated with oxygen isotopes.

Backing up a bit, anemia has many causes, but it often results from diet or from parasites, although it can also be the result of a genetic condition (such as sickle-cell anemia or thalassemia). If a person eats too much maize, for example, that individual is at greater risk of developing a dietary anemia because maize is low in iron. This also holds for millet, which is much lower in iron than its C3 cousins, wheat and barley. So people with high carbon isotope values indicative of C4 (maize/millet) consumption may be expected to have higher frequencies of porotic hyperostosis if diet was the primary contributing factor to anemia. But people who grew up in an area without clean water, particularly an area with a large parasite load like hookworms, may also be at great risk of developing anemia when the parasite attaches to the intestinal lining and robs its host of needed nutrients like iron.

To distinguish between dietary and parasitic anemias as a cause of porotic hyperostosis, Bethany graphed her Machu Picchu individuals on a carbon/oxygen scatterplot. She found two fairly distinct groups of people along the oxygen axis: those with porotic hyperostosis and those without. This clustering she interpreted along the lines of Blom et al. 2005, who argued that a latitudinal patterning of porotic hyperostosis along the coast of Peru and a tendency for childhood anemia to be present in populations from more humid environments may be related to high parasite loads in certain locations rather than to differences in diet. In fact, Bethany’s data did not vary much on the carbon axis, further suggesting a parasitic origin for anemia rather than a dietary one.

Since I have all the same data from my two Roman populations, I created a similar graph to see what patterns there were in the carbon, oxygen, and porotic hyperostosis data. In the scatterplot below, individuals with and without porotic hyperostosis are plotted, and the yellow box represents the “local” oxygen isotope range of Rome:

C and O isotope data from the first molars of two
Imperial Roman (1st-3rd c AD) populations

Unfortunately, my Roman data were not as clear-cut as Bethany’s Peruvian data. Except for the one individual who consumed a C4-heavy diet and suffered from porotic hyperostosis, the rest of the diseased individuals are distributed within -13 to -11 permil on the carbon axis, which represents the average Roman diet of mostly C3 resources like wheat and barley. The people with porotic hyperostosis are spread out on the oxygen axis; however, there are none with oxygen isotope values lower than that of Rome. You may recall from older blog posts (like this one) that oxygen isotope values are more negative in cool, dry climates and more positive in hot, humid climates. It’s actually not a surprise, then, that the non-local people with porotic hyperostosis are on the right side of the graph: they were likely from places warmer and more humid than Rome, which means places along the sea and to the south – places that historically had more malaria, for example, than even Rome did. There are few data points on the left side of the graph, but again, I would expect there to be less malaria and fewer parasites in general in cooler, drier climates like the Apennines that were the source of freshwater springs.

This Roman sample size is small, and the data are not perfectly correlated. A simple t-test, though, actually indicated a statistically significant difference between the oxygen isotope means of the group with porotic hyperostosis and the group without it (t=3.06, p<.005), so with more data, I may find a more robust result. Graphing carbon versus oxygen isotope data has been done for years, but I’d never thought to add porotic hyperostosis as a variable until I heard Bethany’s wonderful talk. This technique has great potential for investigating parasitic disease in ancient Italy, and additional bioarchaeological research - specifically, isotopic analysis - on this front could yield a much stronger argument for the disease ecology of malaria and other parasitic diseases in the peninsula, adding a new dimension to previous osteological studies (e.g., Facchini et al. 2004).

October 6, 2011

Welcome back! Not a lot of Roman bioarch news this week, so I'm stretching my definition a bit to include the stories below.

Excavations and Finds

Two cappuccina burials found in Rome
(credit: ArcheoRivista)

September 26 - A picture and description of two cappuccina graves were posted at ArcheoRivista, although the graves were actually discovered in April. One had been mostly destroyed by tombaroli, but the other is basically intact (see picture). Archaeologists think these were lower-class individuals (as judged by the burial style) and seem to have been found along the Via Valeria. Tombs a cappuccina were quite common in the Imperial period in Rome, and many of the skeletons I studied for my dissertation were from simple cemeteries with these interesting tile-covered burials. Many people aren't aware of the ubiquity of cappuccina tombs, as scholars such as Jocelyn Toynbee give very little space in their books to descriptions of low status burials, preferring to discuss above-ground mausolea and below-ground hypogea. Cappuccina comes from the Italian for "cowl," and Toynbee (1971:102-3) just notes that "the simplest method was to lay the body in the earth, but to cover it with pairs of flat tegulae set gable-wise and generally with imbrices (curved and hollow roofing tiles) along the ridge."

October 5, 2011

I posted a couple months ago when I started looking into submitting manuscripts to bioanthropology journals using LaTeX. Fortunately for me, Elsevier seemed pretty cool with LaTeX submissions. A few minutes ago, I sent my Roman diet article to Elsevier's Journal of Archaeological Science, and it went off with only one minor hitch. I uploaded my .tex file under "Manuscript" but had put my .bib file under "Supplementary Material." Turns out, the system doesn't include supplementary material in a build. So I re-attached the .bib file also as "Manuscript," and the paper built fine.

For those of you thinking about submitting using LaTeX, it's actually quite easy. Simply download the Elsevier class files for the manuscript and the bibliography, write your paper, then upload your .tex and .bib files (and, in my case, .eps figures). On the last screen of the submission process, it'll let you know that it's building your file. Check back in 30 seconds, make sure the PDF looks good, and approve it for submission. Other than the weirdness with the .bib file, the process honestly couldn't have been easier. My macros worked fine, my bibliography looks good, and the figures are all there.

October 4, 2011

Just a few days ago, only the second isotope study of millet consumption in the Roman Empire was published, by Pollard and colleagues in the American Journal of Physical Anthropology. In a small Romano-British cemetery in Kent (late 3rd-early 4th century AD), a salvage archaeology project uncovered a dozen burials that were simple in nature: only coffin nails and hobnails from boots were found in most graves. Among these simple farmers, though, was an individual with a surprisingly high carbon isotope value, so Pollard and colleagues undertook a dietary (C/N) and migration (Sr/O) study of the individuals.

The anomalous partially complete skeleton was that of a male over the age of 45 buried wearing hobnail boots. The individual's nitrogen isotope ratio was a bit high (11.2 permil), indicating aquatic resource consumption, but was not higher than average for Roman Britain. His carbon isotope ratio from collagen, however, came in at -15.2 permil, in stark comparison to the average of the other individuals of -19.8 permil (see below). This difference may not seem dramatic until you factor in the standard deviation - variation within the d13C ratios of the others from the site was only 0.3! This person was therefore eating a whole bunch of C4 resources - millet, sorghum, or animals foddered on those grains.

Figure 3 from Pollard et al. showing the anomalous individual (SK12671)
compared with other Romano-British sites and the two anomalous individuals
published in Muldner et al. 2011.

Evidence of C4 plant consumption is surprisingly absent from the archaeological record of the Roman world, even though authors like Pliny note that millet and beans were frequently eaten together by people in rural Italy. As far as I know, only one bioarchaeological study has been done on skeletons from Italy looking at C4 resource use (Tafuri et al. 2009). Researchers found evidence of millet consumption in the elevated d13C ratios of people from northern Italy in the Bronze Age compared with people in southern Italy. Another Romano-British cemetery yielded two individuals with a mixed C3-C4 diet, where carbon isotope values ranged from -16.8 permil to -15.8 permil. So this new person from Kent provides the highest d13C ratio obtained so far from bone collagen in the Roman period. Below is a graph of the Bronze Age millet-eaters and the Romano-British people from Pollard and colleagues' study:

Curiously, Pollard and colleagues didn't look at carbon values from bone apatite, but they did look at the carbon isotope ratio of the dental apatite, which in this individual was -7.2 permil, also significantly higher than the values from the others, which range from -13.8 to -11.5 permil. This likely means that his C4 resource use was in the form of direct consumption of millet rather than from consuming protein from animals that were foddered on millet.

Finally, they investigated the individual's strontium and oxygen isotope ratios to see if he perhaps immigrated to Britain from an area with more evidence of millet production and consumption, like Italy. This is where the paper gets interesting - the strontium ratio is .708826 and the oxygen (from carbonate) is 26.1 permil. These values are within the range of expectation for someone from southern Britain, so the authors could not rule out a local origin for the man. However, my dissertation work (Killgrove 2010) showed that those values are equally likely to occur in or near Rome - my local strontium range for Rome is .7079-.7102, and the local oxygen range (drawn from Prowse et al. 2007) is 24.9-27.1 permil. Pollard and colleagues suggest that this man may have come from northern Italy, where growing millet was common, but I am not convinced because his strontium isotope ratio of .7088 is far too low for the older geology of northern Italy, unless he was located near the east coast (and then his oxygen ratio should be lower). Rome itself is around .7090, and .7088 - if we assume a western Italian origin - is more like Naples. Granted, it is extraordinarily difficult to pinpoint homeland, and part of this article addresses the problems with identifying immigrants through just Sr and O isotope analyses. As I have started to write up my Sr/O study for publication, it's something I'm keeping in mind. Interestingly, the authors suggest that the inclusion of hobnailed boots in this man's burial may signify that he was "walking back" from Britain to his true homeland.

But the publication of this article - in AJPA no less - makes me excited because I'm sending off my C/N isotope article tomorrow to the Journal of Archaeological Science. And in that article, I have a section on individual ET20, a male in his 30s from the site of Castellaccio Europarco, in the Roman suburbs. ET20 has an astoundingly high d13C ratio: -12.5 permil. This is on par with the isotope ratio of millet itself, and carbon ratios this high tend only to be found in populations that ate maize (corn). However, the d13C ratio from ET20's bone apatite is only -8.6 permil, which is not dramatically higher than the rest of the population, suggesting that this individual was consuming his C4 resources in the form of animals who were foddered on millet. His d15N ratio is 8.3 permil, which is a bit lower than expected from the population, so perhaps he was eating beans along with his millet or millet-fed animals like Pliny suggests. I did do Sr/O on this individual, and they came back at .709631 and 25.3 permil, respectively. Both of these are within my admittedly broad "local" range of Rome, but no one else among the locals has such a high d13C ratio. I suggest in my dissertation (Killgrove 2010) that he may have come from northern Italy - the strontium ratio is higher than expected from Rome, indicating a childhood spent on slightly older geology. I also found with ET20 that his d13C ratio from enamel apatite was -4.0 permil - so he changed his diet between the time he was born and the time he died at Rome. Here's a quick graph from the forthcoming paper showing just how far to the right (C4 use) ET20 is in comparison with others from Castellaccio and Casal Bertone (compare with the graphs above, where no one reaches the high carbon value that ET20 does):

From Killgrove & Tykot, n.d.

At any rate, the person that Pollard and colleagues found (and the two people found by Muldner et al. 2011) show that we have a lot left to learn about C4 resource use in the Roman Empire. Millet may have been considered a substandard grain by many authors, the kind of food that rural or poor people eat, but there is growing evidence that many people were consuming at least a C3-C4 mixed diet and several people were eating quite a bit of millet or animals foddered on the grain. Isotopes are letting us tease out differences in diet at the levels of the individual and the population - especially in Rome, as I've blogged about before here. Although the overall diet mostly tracks with historical and artistic records from the Roman world, the diversity in the lower-class diet is surprising and intriguing, and I think will eventually be able to tell us more about things like status. Watch this space for more on the diet of my Romans as I work through the process of submitting and revising my C/N isotope article this week!

References:

Killgrove, K. (2010). Migration and mobility in Imperial Rome. PhD dissertation, University of North Carolina at Chapel Hill. [PDF]

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is a bioarchaeologist and assistant professor at the University of West Florida. This is her personal blog about archaeology, bioanthropology, and the classical world. Follow her on Twitter (@DrKillgrove) or G+, or follow PbO on Facebook.